Home » Public Forums » GMCnet » Refigerator vent question (In a electric only fridge, is the vent necessary)
| Refigerator vent question [message #268972] |
Tue, 06 January 2015 08:55  |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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A few weeks ago I said something about removing our fridge vent on our 120/12V fridge. I was cautioned by several folks I know and respect that it wasn't a good idea.
So today, I watched the 1977 sales video:
http://www.doityourselfrv.com/vintage-gmc-motorhome-sales-video-will-leave-wanting-re-issue/
None of these coaches have vents for the fridge.
So I come back to this question. In a NON-Absorption fridge, that is no propane option, is the overhead vent necessary for proper function?
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Refigerator vent question [message #268982 is a reply to message #268972] |
Tue, 06 January 2015 09:50  |
Rick Williams
Messages: 256
Registered: July 2004
Karma: 0
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Kerry
My '78 had the all electric frig from the factory. The coach had two louver vents on the side wall and no roof vent. The frig worked fine. I did however install a roof vent when I went to a propane frig.
Rick
Rick Williams
Bliss, Michigan
1978 Eleganza II
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| Re: Refigerator vent question [message #269007 is a reply to message #268972] |
Tue, 06 January 2015 11:39 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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the side vent alone should be enough ventilation for a 12/120 volt refer but if you have a roof vent already there why block it off if it isn't causing a problem? as they say more is better when it comes to ventilation.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Refigerator vent question [message #269012 is a reply to message #269007] |
Tue, 06 January 2015 12:06 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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roy1 wrote on Tue, 06 January 2015 11:39...but if you have a roof vent already there why block it off if it isn't causing a problem? as they say more is better when it comes to ventilation.
I realize it is straining a gnat and swallowing a camel but the lack of aerodynamics of that vent just bugs me. I suppose I could just make an aerodynamic rear facing scoop.
I'm going to be streamlining the AC pod and some other 'stuff' just because I can. I have no doubt that it will NOT have significant impact on fuel mileage but the idea of vertical surfaces in the airflow just doesn't make sense to me.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] Refigerator vent question [message #269018 is a reply to message #269012] |
Tue, 06 January 2015 12:13 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Retaining the roof vent to allow the heat generated by the electric fridge is beneficial.
It also can be used if you wish to install one of the "instant" propane water heaters!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
*[ ]~~~[][ ][|\
*--OO--[]---O-*
> Date: Tue, 6 Jan 2015 11:06:23 -0700
> To: gmclist@temp.gmcnet.org
> From: Pinkertonk@MCHSI.com
> Subject: Re: [GMCnet] Refigerator vent question
>
> roy1 wrote on Tue, 06 January 2015 11:39
>> ...but if you have a roof vent already there why block it off if it isn't causing a problem? as they say more is better when it comes to
>> ventilation.
>
>
> I realize it is straining a gnat and swallowing a camel but the lack of aerodynamics of that vent just bugs me. I suppose I could just make an
> aerodynamic rear facing scoop.
>
> I'm going to be streamlining the AC pod and some other 'stuff' just because I can. I have no doubt that it will NOT have significant impact on fuel
> mileage but the idea of vertical surfaces in the airflow just doesn't make sense to me.
> --
> Kerry Pinkerton
> North Alabama, near Huntsville,
> 77 Eleganza II, "The Lady", 403CI, Manny Brakes, 1 ton, tranny also a 76 Eleganza to be re-bodied as an Art Deco car hauler
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| Re: Refigerator vent question [message #269022 is a reply to message #268972] |
Tue, 06 January 2015 15:33 |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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Hot air rises, so why not have a way for it to escape? JimK has a nice, streamlined top vent that looks much nicer than the early 'mushroom' shaped top vent and is easy to install. Even comes with a solar powered vent fan if you want to pull air over the coils in an absorption fridge.
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: [GMCnet] Refigerator vent question [message #269033 is a reply to message #268972] |
Tue, 06 January 2015 17:53 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Kerry,
I looked at the photos of your GMC on the PhotoSite and note that it has the lower vent and upper vent. If you remove the upper vent
heat can still escape out the side vent, however, the temperature from the top of that vent to the roof will increase as there will
be no air flow in the side and out the top. That will affect the refrigeration cycle negatively and the refrigerator will be less
efficient. The increased heat in the fridge compartment will also radiate into the GMC living space, however, I doubt the amount of
heat radiated will make much difference as you've got roof air.
I reckon you could make a nice looking vent that looked like an upside down boat hull with the prow facing forward and the transom
open to let the heat escape.
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
-----Original Message-----
From: Kerry Pinkerton
A few weeks ago I said something about removing our fridge vent on our 120/12V fridge. I was cautioned by several folks I know and
respect that it wasn't a good idea.
So today, I watched the 1977 sales video:
http://www.doityourselfrv.com/vintage-gmc-motorhome-sales-video-will-leave-wanting-re-issue/
None of these coaches have vents for the fridge.
So I come back to this question. In a NON-Absorption fridge, that is no propane option, is the overhead vent necessary for proper
function?
--
Kerry
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Refigerator vent question [message #269035 is a reply to message #268972] |
Tue, 06 January 2015 18:11 |
bobby5832708
Messages: 237
Registered: November 2006
Location: Winter Springs FL
Karma: 3
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I think I've got the only GMC (the only one I've ever seen) without any external refrig vents. I still have the original Norcold compressor-style fridge and it works fine without the external vents except on hot days. Being in Florida there's quite a few hot days.
What I did is mount an old computer fan in the cabinet next to the refrig so it blows air into the cavity behind the refrigerator and helps move the hot air out the internal vents that are both above and below the Norcold. I wired the fan to the compressor, put a diode inline to make DC (really noisy DC), and reduced the voltage with a resistor (ohms unknown right now). It blows an adequate amount of air and is pretty quiet. One of these years I will swap the computer fan with a small squirrel cage blower to further increase the airflow and, in theory, reduce what little noise there is now. It's been this way for 7 years now so I'm in no hurry to add yet another project to the list.
Anybody else have a GMC motorhome (not Transmode) that has never had refrig vents? I can't believe I've got the only one.
Bob Heller
2017 Winnebago 29VE
Winter Springs FL
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| Re: [GMCnet] Refigerator vent question [message #269093 is a reply to message #269089] |
Wed, 07 January 2015 08:10 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Tangerine wrote on Wed, 07 January 2015 08:43
My coach has the original Norcold all electric refrig with no external
venting.
--
Gary W. Mills
Livonia, MI
. ___________
./_][__][] []| 1974 GMC M/H
.*O-------OO-* Painted Desert
The side and top vents in my 73-23 were obviously added later and poorly.
There is a not in the coaches file that this was a possible correction for coached in hot areas.
There is also a joke attached....
On our maiden excursion, in Somewhere Minnesota in October, it was 20°F and the nice new heater was beating cheeks to keep up. when I walked past the reefer, there was cold pouring out onto my feet. Yes, they had put in the vents, but never closed off the designed in ventilation above and below the reefer. They are plugged up now.
In Michigan, the old NoCold will do well without the external vents until it dies.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Refigerator vent question [message #269100 is a reply to message #269093] |
Wed, 07 January 2015 08:42 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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On those 73 models with all electric friges, the grate at the top of the
frig on the inside is supposed to help flow enough air to keep things
going. The more air flow you can get the better and gas units need more
venting. Just up to you, if you have a roof vent I would keep it, an
intake and outtake vents would always help but do ya haveta-- probably not.
Jim Bounds
-------------------------
On Wed, Jan 7, 2015 at 9:10 AM, Matt Colie wrote:
> Tangerine wrote on Wed, 07 January 2015 08:43
>> My coach has the original Norcold all electric refrig with no external
>> venting.
>> --
>> Gary W. Mills
>> Livonia, MI
>> . ___________
>> ./_][__][] []| 1974 GMC M/H
>> .*O-------OO-* Painted Desert
>
> The side and top vents in my 73-23 were obviously added later and poorly.
> There is a not in the coaches file that this was a possible correction for
> coached in hot areas.
>
> There is also a joke attached....
> On our maiden excursion, in Somewhere Minnesota in October, it was 20°F
> and the nice new heater was beating cheeks to keep up. when I walked past
> the reefer, there was cold pouring out onto my feet. Yes, they had put in
> the vents, but never closed off the designed in ventilation above and below
> the reefer. They are plugged up now.
>
> In Michigan, the old NoCold will do well without the external vents until
> it dies.
>
> Matt
> --
> Matt & Mary Colie - Members GMCMI, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
> SE Michigan - Twixt A2 and Detroit
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> Unsubscribe or Change List Options:
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| Re: Refigerator vent question [message #269102 is a reply to message #268972] |
Wed, 07 January 2015 09:23 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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The heat to be rejected is the heat removed from the refer PLUS the heat of electrical energy used. Might pass through the outer wall and interior furniture on a cooler day, but not so well as it gets hot out and or inside. It's that old Delta T thing you can't argue with.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Refigerator vent question [message #269106 is a reply to message #268972] |
Wed, 07 January 2015 09:32 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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I agree with the comments about the heat needing to go 'somewhere'. I'm still wondering why, in 1976/77 none of the coaches in the video had roof vents. Did GMC not, by this time, understand the thermodynamics requirements of the fridges or was this just a marketing thing and the 'production' coaches would have the vents.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] Refigerator vent question [message #269111 is a reply to message #269106] |
Wed, 07 January 2015 10:10 |
Dave Mumert
Messages: 272
Registered: February 2004
Location: Olds, AB, Canada
Karma: 0
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Hi Kerry
The largest Nova Kool unit draws 5.2 amps at 12 volts when running, that is less than 75 watts. Cooling the food in the fridge
would add to the heat output. If you fill it with warm beer it will throw off a lot of heat until it cools down, then not so much.
That amount of heat could be a problem when it is hot and you cannot run the AC.
Personally I would rather deal with the extra heat and have a cleaner exterior, but I live in Canada so the extra heat may be
welcome, I'm sure the dual Fantastic vents will be able to deal with it.
Dave Mumert
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| Re: Refigerator vent question [message #269114 is a reply to message #269106] |
Wed, 07 January 2015 10:51 |
bryant374
Messages: 563
Registered: May 2004
Location: Pleasant Valley, NY 12569
Karma: 1
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A few details of original GMC refigerator venting:
Only 1973 & most 1974s did not have the factory installed refer side/top vents. The MH shown in the Mini Theatre film was a 1973 (without vents).
The following Technical Bulletin describes how the dealer is to retro-fit a vent (note, only if the customer complains about poor performance, 6 pgs).
http://www.gmcmhphotos.com/photos/production-changes/p55153-75-tm-9-001.html
I spoke with John Locklin, GMC MH Body Engineer whose responsibility would have been the vent, as well as all body areas, he said, "I forgot to include it". With MANY things going on at the time, probably not surprising.
Note: the earlier prototypes had vents.
Question: Since the refer heater stack requires the same temperature to change the charge from liquid to gas,how much more heat would you expect the propane vs electrical system produces?
Bill Bryant
PO 1976~PB (owned 34 years)
1914 Ford (owned 70 years)
1965 Corvette (owned 39 years)
GMC Motorhome History
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| Re: [GMCnet] Refigerator vent question [message #269126 is a reply to message #269003] |
Wed, 07 January 2015 12:14 |
<rallymaster
Messages: 361
Registered: May 2014
Karma: 2
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Side note on NoCold fridges.
There is no warranty on N641 AC/LP gas operated "NoCold" fridges mounted
in the original fridge cabinet in a GMC motorhome.
The vents don't match the Norcold vent and baffle requirements listed
somewhere around page 4 in the installation manual. Even installing all
the baffles they want won't help as the lower intake vent is not even
with or below the floor of the fridge compartment.
If you didn't follow the instructions exactly, that's obviously why your
fridge failed, even if the earlier 663 6 cu. ft. fridge lasted for years
with no problems.
RonC
On Wed, 07 Jan 2015 07:10:58 -0700 Matt Colie
writes:
> Tangerine wrote on Wed, 07 January 2015 08:43
>> My coach has the original Norcold all electric refrig with no
> external
>> venting.
>> --
>> Gary W. Mills
>> Livonia, MI
>> . ___________
>> ./_][__][] []| 1974 GMC M/H
>> .*O-------OO-* Painted Desert
>
> The side and top vents in my 73-23 were obviously added later and
> poorly.
> There is a not in the coaches file that this was a possible
> correction for coached in hot areas.
>
> There is also a joke attached....
> On our maiden excursion, in Somewhere Minnesota in October, it was
> 20°F and the nice new heater was beating cheeks to keep up. when I
> walked past
> the reefer, there was cold pouring out onto my feet. Yes, they had
> put in the vents, but never closed off the designed in ventilation
> above and below
> the reefer. They are plugged up now.
>
> In Michigan, the old NoCold will do well without the external vents
> until it dies.
>
> Matt
> --
> Matt & Mary Colie - Members GMCMI, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied
> Control Arms
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: Refigerator vent question [message #269130 is a reply to message #268972] |
Wed, 07 January 2015 13:18 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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My coach has only side vents, added by Sirum when the Norcold went in. It has always performed OK, but when I installed a CO alarm, it indicates there's some reefer exhaust making it into the coach. So, I had Camping Whirled get me another of the upper small aide vents - the original has cracked - and I installed two muffin fans inside it which are powered by the 12V going to the burner solenoid. So far, no problem with AC operation, but if performance suffers, I'll add a 110V relay to turn them on when the AC is on.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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